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Making inductors
Hi,
I am new to ham radio. Well I found lots of QRP receiver circuit on web, I tried to build some. Everything going to be OK, except making coil inductors. I don't know how to calculate them, with type I need (air core or slug tuned), what a difference between coil and RF choke. Let's assume I need a 100uH coil. How to star making it. I looked for factory made coil at my radio shack store, but I only found bobbin for coil. If you know any interesting link on this topic, please let me know. I'll appreciate any comment or help. Thanks in advice, Edgar 73 |
Inductors have several different and important properties besides
inductance -- loss (Q), stray capacitance, and temperature sensativity among them. If the coil is wound on a magnetic core and DC is passed through it, core saturation can be an important consideration. Which properties are important depends on the application. So you'll very often get badly reduced performance, or a non-working circuit, if you substitute one type of inductor for another without knowing much about them. Consequently, a decently written article should include details about how each inductor is made. If that information isn't provided, I suggest contacting the author of the article to find out what he used. That's just about the only way of insuring that you'll get the same performance the author did. If you're interested in building QRP receivers, there are a number of sources where you can find good circuits which include the necessary information to build them. The very best, although perhaps a bit expensive for a beginner, is _Experimental Methods in RF Design_, available from the ARRL and other dealers. Less expensive, and a tremendous bargain, is a CD containing the contents of 109 issues of _Sprat_, the magazine of the G-QRP club. For only $25 + $4 shipping ($15 + $4 for G-QRP club members), you get an amazing amount and variety of information. It's available in the U.S. from Kanga US, contact Bill Kelsey at . To order from other contries, go to http://www.gqrp.com and click the "Club Sales" link. Roy Lewallen, W7EL Qas wrote: Hi, I am new to ham radio. Well I found lots of QRP receiver circuit on web, I tried to build some. Everything going to be OK, except making coil inductors. I don't know how to calculate them, with type I need (air core or slug tuned), what a difference between coil and RF choke. Let's assume I need a 100uH coil. How to star making it. I looked for factory made coil at my radio shack store, but I only found bobbin for coil. If you know any interesting link on this topic, please let me know. I'll appreciate any comment or help. Thanks in advice, Edgar 73 |
Inductors have several different and important properties besides
inductance -- loss (Q), stray capacitance, and temperature sensativity among them. If the coil is wound on a magnetic core and DC is passed through it, core saturation can be an important consideration. Which properties are important depends on the application. So you'll very often get badly reduced performance, or a non-working circuit, if you substitute one type of inductor for another without knowing much about them. Consequently, a decently written article should include details about how each inductor is made. If that information isn't provided, I suggest contacting the author of the article to find out what he used. That's just about the only way of insuring that you'll get the same performance the author did. If you're interested in building QRP receivers, there are a number of sources where you can find good circuits which include the necessary information to build them. The very best, although perhaps a bit expensive for a beginner, is _Experimental Methods in RF Design_, available from the ARRL and other dealers. Less expensive, and a tremendous bargain, is a CD containing the contents of 109 issues of _Sprat_, the magazine of the G-QRP club. For only $25 + $4 shipping ($15 + $4 for G-QRP club members), you get an amazing amount and variety of information. It's available in the U.S. from Kanga US, contact Bill Kelsey at . To order from other contries, go to http://www.gqrp.com and click the "Club Sales" link. Roy Lewallen, W7EL Qas wrote: Hi, I am new to ham radio. Well I found lots of QRP receiver circuit on web, I tried to build some. Everything going to be OK, except making coil inductors. I don't know how to calculate them, with type I need (air core or slug tuned), what a difference between coil and RF choke. Let's assume I need a 100uH coil. How to star making it. I looked for factory made coil at my radio shack store, but I only found bobbin for coil. If you know any interesting link on this topic, please let me know. I'll appreciate any comment or help. Thanks in advice, Edgar 73 |
"Qas" wrote in message om... Hi, I am new to ham radio. Well I found lots of QRP receiver circuit on web, I tried to build some. Everything going to be OK, except making coil inductors. I don't know how to calculate them, with type I need (air core or slug tuned), what a difference between coil and RF choke. Let's assume I need a 100uH coil. How to star making it. I looked for factory made coil at my radio shack store, but I only found bobbin for coil. If you know any interesting link on this topic, please let me know. I'll appreciate any comment or help. 100 uH is quite a lot of inductance for a radio circuit, expecially at HF. Inductors around 10 uH or less are very easy to make using toroidal cores. For instance, a 5 uH inductor is about 32 turns on a T50-2 core. I use a simple Excel spreadsheet for this sort of thing. RF chokes are basically inductors, but specifically intended for stopping RF from going somewhere unwanted. They are usually wound on ferrite cores, and tend to have fairly high inductance values. They are used on their own, usually, unlike coils, which tend to be used with capacitors. RF chokes have a self-resonant frequency due to their self-capcitance - this needs to be checked when using them and the self-resonant frequency avoided. 73, Leon -- Leon Heller, G1HSM http://www.geocities.com/leon_heller |
"Qas" wrote in message om... Hi, I am new to ham radio. Well I found lots of QRP receiver circuit on web, I tried to build some. Everything going to be OK, except making coil inductors. I don't know how to calculate them, with type I need (air core or slug tuned), what a difference between coil and RF choke. Let's assume I need a 100uH coil. How to star making it. I looked for factory made coil at my radio shack store, but I only found bobbin for coil. If you know any interesting link on this topic, please let me know. I'll appreciate any comment or help. 100 uH is quite a lot of inductance for a radio circuit, expecially at HF. Inductors around 10 uH or less are very easy to make using toroidal cores. For instance, a 5 uH inductor is about 32 turns on a T50-2 core. I use a simple Excel spreadsheet for this sort of thing. RF chokes are basically inductors, but specifically intended for stopping RF from going somewhere unwanted. They are usually wound on ferrite cores, and tend to have fairly high inductance values. They are used on their own, usually, unlike coils, which tend to be used with capacitors. RF chokes have a self-resonant frequency due to their self-capcitance - this needs to be checked when using them and the self-resonant frequency avoided. 73, Leon -- Leon Heller, G1HSM http://www.geocities.com/leon_heller |
Frank - your email address bounced:
Subject: Making inductors Date: Monday, September 08, 2003 9:18 AM Frank I got mine from Kanga U.S., but I see Kanga U.K isn't selling anything, and they only list one book. I also suspected G-QRP as a source, but they don't show it on their web site. If there is a U.K. Source, George Dobbs, G3RJV, would know. In fact, I think I saw it at George's booth at Dayton. Bill Kelsey at Kanga U.S. is a nice guy and easy to deal with (http://www.bright.net/~kanga/kanga) but I suspect there is a UK source somewhere which could be a lot easier for you. The book is $20 U.S. so it's probably going to be 20 pounds by the time you get it across the pond. Paul Harden does this wonderful artwork which makes the book a real joy. It's such a dense collection of reference info that it really is a "must have" for a builder. It may be a little more U.S. centric than you would like. Although he does show drill sizes for various metric screws, his transistor table pretty much sticks to the 2N and 2SC types. Still, it's almost worth it for the wonderful capacitor section. And he does show all the common toroid mixes, how to wind toroids, and he has some nice charts of inductance and Q for the more common mixes. 72/73 de WB8RCR http://www.qsl.net/wb8rcr didileydadidah QRP-L #1446 Code Warriors #35 ----- Original Message ----- Sent: Friday, September 05, 2003 7:48 AM Subject: Making inductors As always, all the equations are in the handbook. Paul Harden's "Data Book for Homebrewers and QRPers" has all the tables, without the explanations, and it's a lot more compact (and cheaper besides). ======== Hi, Could you please provide me with a source where to obtain this book .. I am in Scotland UK but can order in the USA Approx cost ? TIA Frank GM0CSZ / KN6WH |
Frank - your email address bounced:
Subject: Making inductors Date: Monday, September 08, 2003 9:18 AM Frank I got mine from Kanga U.S., but I see Kanga U.K isn't selling anything, and they only list one book. I also suspected G-QRP as a source, but they don't show it on their web site. If there is a U.K. Source, George Dobbs, G3RJV, would know. In fact, I think I saw it at George's booth at Dayton. Bill Kelsey at Kanga U.S. is a nice guy and easy to deal with (http://www.bright.net/~kanga/kanga) but I suspect there is a UK source somewhere which could be a lot easier for you. The book is $20 U.S. so it's probably going to be 20 pounds by the time you get it across the pond. Paul Harden does this wonderful artwork which makes the book a real joy. It's such a dense collection of reference info that it really is a "must have" for a builder. It may be a little more U.S. centric than you would like. Although he does show drill sizes for various metric screws, his transistor table pretty much sticks to the 2N and 2SC types. Still, it's almost worth it for the wonderful capacitor section. And he does show all the common toroid mixes, how to wind toroids, and he has some nice charts of inductance and Q for the more common mixes. 72/73 de WB8RCR http://www.qsl.net/wb8rcr didileydadidah QRP-L #1446 Code Warriors #35 ----- Original Message ----- Sent: Friday, September 05, 2003 7:48 AM Subject: Making inductors As always, all the equations are in the handbook. Paul Harden's "Data Book for Homebrewers and QRPers" has all the tables, without the explanations, and it's a lot more compact (and cheaper besides). ======== Hi, Could you please provide me with a source where to obtain this book .. I am in Scotland UK but can order in the USA Approx cost ? TIA Frank GM0CSZ / KN6WH |
Tnx for the info re Paul Harden's book .
My email address is OK but using a spam remover prog ,I might have 'accidentically 'bounced your message ,sorry for that. I am a G-QRP Club member and shall check with George , G3RJV re availability. Perhaps you can give me the book's ISBN number ,such that I can order in the US if necessary and get it sent to my son who lives in California. TIA for your advice Best wishes Frank , GM0CSZ / KN6WH I got mine from Kanga U.S., but I see Kanga U.K isn't selling anything, and they only list one book. I also suspected G-QRP as a source, but they don't show it on their web site. If there is a U.K. Source, George Dobbs, G3RJV, would know. In fact, I think I saw it at George's booth at Dayton. Bill Kelsey at Kanga U.S. is a nice guy and easy to deal with (http://www.bright.net/~kanga/kanga) but I suspect there is a UK source somewhere which could be a lot easier for you. The book is $20 U.S. so it's probably going to be 20 pounds by the time you get it across the pond. Paul Harden does this wonderful artwork which makes the book a real joy. It's such a dense collection of reference info that it really is a "must have" for a builder. It may be a little more U.S. centric than you would like. Although he does show drill sizes for various metric screws, his transistor table pretty much sticks to the 2N and 2SC types. Still, it's almost worth it for the wonderful capacitor section. And he does show all the common toroid mixes, how to wind toroids, and he has some nice charts of inductance and Q for the more common mixes. 72/73 de WB8RCR http://www.qsl.net/wb8rcr didileydadidah QRP-L #1446 Code Warriors #35 |
Tnx for the info re Paul Harden's book .
My email address is OK but using a spam remover prog ,I might have 'accidentically 'bounced your message ,sorry for that. I am a G-QRP Club member and shall check with George , G3RJV re availability. Perhaps you can give me the book's ISBN number ,such that I can order in the US if necessary and get it sent to my son who lives in California. TIA for your advice Best wishes Frank , GM0CSZ / KN6WH I got mine from Kanga U.S., but I see Kanga U.K isn't selling anything, and they only list one book. I also suspected G-QRP as a source, but they don't show it on their web site. If there is a U.K. Source, George Dobbs, G3RJV, would know. In fact, I think I saw it at George's booth at Dayton. Bill Kelsey at Kanga U.S. is a nice guy and easy to deal with (http://www.bright.net/~kanga/kanga) but I suspect there is a UK source somewhere which could be a lot easier for you. The book is $20 U.S. so it's probably going to be 20 pounds by the time you get it across the pond. Paul Harden does this wonderful artwork which makes the book a real joy. It's such a dense collection of reference info that it really is a "must have" for a builder. It may be a little more U.S. centric than you would like. Although he does show drill sizes for various metric screws, his transistor table pretty much sticks to the 2N and 2SC types. Still, it's almost worth it for the wonderful capacitor section. And he does show all the common toroid mixes, how to wind toroids, and he has some nice charts of inductance and Q for the more common mixes. 72/73 de WB8RCR http://www.qsl.net/wb8rcr didileydadidah QRP-L #1446 Code Warriors #35 |
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